[kypfer]

Resurrecting this old thread.

I received my Zeiss Jena 35 2.8 (zebra) today. Love the close focus ability! But my M42 to K adapter doesn't have the proper flange to cause the aperture pin to depress. It only shoots wide open at the moment. What's my best option, just a different adapter, and if so is the authentic Pentax Adapter K a good choice?

Does the lens have an A/M switch? If so, preset the aperture you want, focus as required, then operate (and hold, if necessary) the A/M switch in the M position to meter and make your exposure.
If there's no A/M switch, the Pentax Adapter K is not the best choice if you don't want to modify the lens, 'cos it has no facility to operate the aperture pin.
As far as I'm aware most/all Pentax 42-screw lenses had an A/M switch, so there was no need to consider the need to actuate the aperture pin when the adaptor was designed.
So, you're either needing to find one of the uncommon aftermarket adapters with the internal flange that'll operate the pin for you, only use the lens wide open, or succumb to necessity and modify/adjust the mechanism to keep the pin depressed all the time.
Enjoy

[gatorguy]

Does the lens have an A/M switch? If so, preset the aperture you want, focus as required, then operate (and hold, if necessary) the A/M switch in the M position to meter and make your exposure.
If there's no A/M switch, the Pentax Adapter K is not the best choice if you don't want to modify the lens, 'cos it has no facility to operate the aperture pin.
As far as I'm aware most/all Pentax 42-screw lenses had an A/M switch, so there was no need to consider the need to actuate the aperture pin when the adaptor was designed.
So, you're either needing to find one of the uncommon aftermarket adapters with the internal flange that'll operate the pin for you, only use the lens wide open, or succumb to necessity and modify/adjust the mechanism to keep the pin depressed all the time.
Enjoy

My Tam and Pentax M42's do have an A/M switch. The original version of the Flektogon does not. Do you have any suggestion of a third party adapter with a flange for the pin, or am I better off with a partial disassembly and shimming the pin up which I found was one solution, or "something else"?

Then again using it wide-open is probably the most likely scenario anyway. I might be needlessly trying to fix an issue which won't be a negative.

[vonBaloney]

My Tam and Pentax M42's do have an A/M switch. The original version of the Flektogon does not. Do you have any suggestion of a third party adapter with a flange for the pin, or am I better off with a partial disassembly and shimming the pin up which I found was one solution, or "something else"?

Then again using it wide-open is probably the most likely scenario anyway. I might be needlessly trying to fix an issue which won't be a negative anyway.

Your options are:

-- An adapter that pushes down the pin when mounted. For infinity-focus versions I remember one existing (although I never had one) but may be hard to find.

-- Open up the mount and figure out how to shim it. I don't know about this particular mount -- some are trivial to do, some aren't.

-- Superglue the pin down from the outside (this is reversible with acetone if you do it carefully and keep the glue on the outside). Slightly risky because of the glue (and maybe later with the acetone if you want to undo it), but also the quickest and easiest. (I've done it lots of times with lenses I never plan on selling.) People worry about fogging the lens with the fumes, but that risk only exists for a few minutes really while the glue dries -- just block off the rear glass with something and do it in a well-ventilated area and it is fine.

[gatorguy]

Your options are:

-- An adapter that pushes down the pin when mounted. For infinity-focus versions I remember one existing (although I never had one) but may be hard to find.

-- Open up the mount and figure out how to shim it. I don't know about this particular mount -- some are trivial to do, some aren't.

-- Superglue the pin down from the outside (this is reversible with acetone if you do it carefully and keep the glue on the outside). Slightly risky because of the glue (and maybe later with the acetone if you want to undo it), but also the quickest and easiest. (I've done it lots of times with lenses I never plan on selling.) People worry about fogging the lens with the fumes, but that risk only exists for a few minutes really while the glue dries -- just block off the rear glass with something and do it in a well-ventilated area and it is fine.

Thanks for the advice! I'll try the first suggestion.

I found only one anywhere but it was at Adorama, a Kipon M42 to Pentax K which should work. Somewhere I saw a mention that it might not depress the pin enough to fully engage it and thus limiting the aperture range so I guess we'll see. If that doesn't work I'll contemplate one of the other two, or just go full-open

[kypfer]

Thanks for the advice! I'll try the first suggestion.

I found only one anywhere but it was at Adorama, a Kipon M42 to Pentax K which should work. Somewhere I saw a mention that it might not depress the pin enough to fully engage it and thus limiting the aperture range so I guess we'll see. If that doesn't work I'll contemplate one of the other two, or just go full-open

That Kipon adapter looks to be the tool for the job … pricey, but you get to retain the originality of your lenses … personally, I'm with vonBaloney, superglue it and done with it
Enjoy

[gatorguy]

That Kipon adapter looks to be the tool for the job … pricey, but you get to retain the originality of your lenses … personally, I'm with vonBaloney, superglue it and done with it
Enjoy

I received the Kipon this afternoon and it works perfectly with the pin appearing to fully depress as it should. I suspected it would not and instead only give me partial I now have full aperture control.

Makes up for a Helios 44M also received today that's probably a paperweight.

[cnarchitect]

A Chinese local small manufucturer supplys quite good quality Brass M42/PK adaptor with flange. Called "Lee adaptor".About 15 pounds for each. I bought a dozen of them myself. They are actually quite good; have enough damping that allows you mount off the lens with adaptor stays on; eventually covert M42 lens into a PK mount. Not quite sure avalible oftenly on eBay. They are sold on Chinese site; Taobao

Attached Images

 

[Jonathan Mac]

I just don't buy M42 lenses without an A/M switch, they're too much bother.

[gatorguy]

I just don't buy M42 lenses without an A/M switch, they're too much bother.

I'd agree. I didn't know this one didn't until I received it. Now I'll know to watch for that.

[vonBaloney]

There are some very fine m42 lenses that have a pin but no A/M switch. You can always glue them -- takes 2 minutes (and some drying time).

[i_trax]

Before I purchased this black one with the flange ( infinity focus preserved ) I used to just band the pin slightly and push it in ( you could easy undo it ).
This black adapter was available to purchase via eBay from Lithuania. It was a bit cheaper than Kipon.

[mlag]

I got my new Kipon one today and it is just too large. It will press into the opening on the camera but is too tight to turn. It is the ring that fits flush into the recess. I think it is probably just a layer of paint too large so intend to rub it down rather than spending money posting it back to Germany. In the meanwhile I have ordered one of the black ones. Can anyone suggest something abrasive enough to skim the adapter without damaging it?

Grumble grumble grumble

Same with my kipon copy on my K3II. But on older analog bodies like MZ-7 it is looser and ok....

I tried to measure it but the difference is paper-thin...below 0,08 mm / 0.003 inch. The recessed ring on my 4 bodies varies between 48,36 and 48,44 mm maximum (The tool I used has an accuracy of 0,02 mm , so it is bit on the edge of accuracy and successive measurements differ a bit,...)

I sanded it a bit (to reduce diameter, exterior ring) and now works smooth.

I used a drill at low speed and little rotating head (kind of abbrasive stone material , used to remove sharp edges of metal. 3 x360⁰ turns of the kipon against it with low pressure was enough...

PS: works prefect on my Jena flektagon 35mm f2.8 zebra type

[gatorguy]

Same with my kipon copy on my K3II. But on older analog bodies like MZ-7 it is looser and ok....

I tried to measure it but the difference is paper-thin...below 0,08 mm / 0.003 inch. The recessed ring on my 4 bodies varies between 48,36 and 48,44 mm maximum (The tool I used has an accuracy of 0,02 mm , so it is bit on the edge of accuracy and successive measurements differ a bit,...)

I sanded it a bit and now works smooth.

I used a drill at low speed and little rotating head (kind of abbrasive stone material , used to remove sharp edges of metal after drilling, like this https://hogaki.com/data/product/lg/ila-14350-6.jpg ). 3 360⁰ turns of the kipon against it with low pressure was enough...

PS: works prefect on my Jena flektagon 35mm f2.8 zebra type

I bought the same Kipon adapter and for the same lens! Yes the mount is snug, but it fits fine.

[mlag]

I bought the same Kipon adapter and for the same lens! Yes the mount is snug, but it fits fine.

In my case it was hardly possible to enter the kipon+lens into mount on the k3II, in any case not full depth , and impossible to rotate it. On the older body it was no problem, so there is some variation in the pentax body mounts. But after sanding perfect on this lens and body. Only pity that there is a severe storm ongoing, otherwise I was out with my camera...

[photogem]

There are a few very usefull links which I have found over the years for how to convert

either M42 lenses (never Pentax but third party) with that aperture pin that sticks out too much:
M42 Lens Aperture Pin | The pin visible near the top left co? | Flickr
Converting an Auto-Aperture M42 Lens to Manual Aperture | Flickr

and here in the German Pentaxians-forum (you need to register there to see all photos or links!):
https://www.pentaxians.de/40456504nx51499/objektive-f27/m42-stoessel-und-ble...mm-t19078.html

If one wants to convert an M42 lens with one of those cheap chinese M42 adapters by keeping the adapter permanently on your M42 lens,
one can with just unscrew this tiny screw on the M42 adapter and take of that spring that now comes lose. Then one can screw the M42 adapter very tightly onto the M42 lens (even use superglue) and then insert that tiny screw again and tighten it as well.

But the most complete conversion is shown here with this tutorial (again, here you must register to see the photos, but it is worth it):
https://www.pentaxians.de/40456504nx51499/tipps-und-tricks-f41/tutorial-m42-...en-t27332.html

I'll try to link the photos at least:
Photo 1: https://pentaxians.eu/forumimages/2017/5274/5274_2017090303_img2946.jpg
Photo 2: https://pentaxians.eu/forumimages/2017/5274/5274_2017090308_img2948.jpg
Photo 3: https://pentaxians.eu/forumimages/2017/5274/5274_2017090310_img2949.jpg
Photo 4: https://pentaxians.eu/forumimages/2017/5274/5274_2017090312_img2950.jpg
Photo 5: https://pentaxians.eu/forumimages/2017/5274/5274_2017090315_img2954.jpg

So you need to

1. Mark the position where to drill the hole
2. With a center-punch insert that tiny indention so your drill will for sure find the exact position
3. First drill a 1mm, then 2.2 mm hole